<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
			* {
				padding: 0px;
				margin: 0px;
				/* 怪异盒模型 */
				box-sizing: border-box;
			}
			
			.div1 {
				width: 100px;
				height: 100px;
				padding: 5px;
				border: 1px solid #f00;
				margin: 5px;
				
			}
		</style>
	</head>
	<body>
		<div class="div1">
			我是div
		</div>
	</body>
</html>